Semiconductor device

ABSTRACT

It is an object of the present invention to provide a semiconductor device in which data can be written except when manufacturing the semiconductor device and that counterfeits can be prevented. Moreover, it is another object of the invention to provide an inexpensive semiconductor device including a memory having a simple structure. The semiconductor device includes a field effect transistor formed over a single crystal semiconductor substrate, a first conductive layer formed over the field effect transistor, an organic compound layer formed over the first conductive layer, and a second conductive layer formed over the organic compound layer, and a memory element includes the first conductive layer, the organic compound, and the second conductive layer. According to the above structure, a semiconductor device which can conduct non-contact transmission/reception of data can be provided by possessing an antenna.

TECHNICAL FIELD

The present invention relates to a semiconductor device having a memoryelement. More specifically, the invention relates to a semiconductordevice including an organic compound layer as the memory element.

BACKGROUND ART

In recent years, electronic devices using organic materials are widelydeveloped, and organic ELs which are light emitting elements, organicTFTs, and the like are developed. In addition, memory elements usingorganic materials, for example, mask ROMs and the like utilizing organicdiodes, are studied (for example, Patent Document 1: Japanese PatentPublication No. 2001-516964). In these memory elements, writing (writingonce, reading many) data cannot be conducted except when manufacturingthe memory element; therefore, the memory elements are inconvenient.

DISCLOSURE OF INVENTION

It is an object of the present invention to provide a semiconductordevice in which data can be written except when manufacturing a chip andthat counterfeits can be prevented. Moreover, it is another object ofthe invention to provide an inexpensive semiconductor device including amemory element having a simple structure.

To solve the above problem, a means hereinafter is adopted in theinvention.

One embodiment of the invention is that a semiconductor device includesa field effect transistor formed over a single crystal semiconductorsubstrate; and a memory circuit provided above the field effecttransistor, wherein the field effect transistor is formed using thesingle crystal semiconductor substrate as a channel region, wherein thememory circuit includes an organic memory element in which a firstconductive layer, an organic compound layer, and a second conductivelayer are sequentially stacked. The term “organic memory element” hererefers to an element having a structure in which an organic compoundlayer is interposed between at least a pair of conductive layers.

Another embodiment of the invention is that a semiconductor deviceincludes a field effect transistor formed using a single crystalsemiconductor substrate as a channel region; a memory circuit providedabove the field effect transistor; and a conductive layer serving as anantenna, wherein the memory circuit includes an organic memory elementin which a first conductive layer, an organic compound layer, and asecond conductive layer are sequentially stacked, and wherein theconductive layer serving as the antenna and the first conductive layerare provided in a same layer.

Another embodiment of the invention is that a semiconductor deviceincludes a field effect transistor formed using a single crystalsemiconductor substrate as a channel region; a memory circuit providedabove the field effect transistor; and a conductive layer serving as anantenna which is provided above the memory circuit, wherein the memorycircuit includes an organic memory element in which a first conductivelayer, an organic compound layer, and a second conductive layer aresequentially stacked, and wherein the conductive layer serving as theantenna is pasted so as to be electrically connected to the field effecttransistor.

Another embodiment of the invention provides a semiconductor devicehaving the above structure, wherein a memory circuit includes an organicmemory element having a first conductive layer electrically connected toa field effect transistor, an insulating layer provided so as to coverthe edge portion of the first conductive layer, an organic compoundlayer provided over the first conductive layer and the insulating layer,and a second conductive layer provided over the organic compound layer.

Another embodiment of the invention provides a semiconductor devicehaving the above structure, wherein a memory circuit includes an organicmemory element having a first conductive layer electrically connected toa field effect transistor, an insulating layer provided so as to coverthe edge portion of the first conductive layer, an organic compoundlayer provided so as to cover the first conductive layer which is notcovered with the insulating layer and the edge portion of the insulatinglayer, and a second conductive layer provided so as to cover the organiccompound layer and the insulating layer which is not covered with theorganic compound layer.

Another embodiment of the invention provides a semiconductor devicehaving the above structure, wherein one or both of the first conductivelayer and the second conductive layer have a light-transmittingproperty. This structure is required when data is written (written once,read many) to a memory circuit by optical action.

Another embodiment of the invention provides a semiconductor devicehaving the above structure, wherein resistance of an organic memoryelement changes irreversibly by writing processing which appliesvoltage.

Another embodiment of the invention provides a semiconductor devicehaving the above structure, wherein the distance between the firstconductive layer and the second conductive layer of the organic memoryelement changes when data is written to the memory circuit. The changeof the distance between the first conductive layer and the secondconductive layer by writing data is different depending on the locationof the organic memory element, and the distance is wide in one locationand narrow in another location.

Another embodiment of the invention provides a semiconductor devicehaving the above structure, wherein the organic compound layer is formedfrom an electron transporting material or a hole transporting material.More specifically, the conductivity of the organic compound layer is10⁻¹⁵ S/cm or more to 10⁻³ S/cm or less.

Another embodiment of the invention provides a semiconductor devicehaving the above structure, wherein the film thickness of the organiccompound layer is 5 nm to 60 nm.

Another embodiment of the invention provides a semiconductor devicehaving the above structure, wherein one or a plurality of memoriesselected from a DRAM (Dynamic Random Access Memory), a SRAM (StaticRandom Access Memory), a FeRAM (Ferroelectric Random Access Memory), amask ROM (Read Only Memory), a PROM (Programmable Read Only Memory), anEPROM (Electrically Programmable Read Only Memory), an EEPROM(Electrically Erasable Read Only Memory), and a flash memory is includedas the memory circuit as well as the organic memory element.

Another embodiment of the invention provides a semiconductor devicehaving the above structure, wherein one or a plurality of circuitsselected from a power supply circuit, a clock generator circuit, a datademodulator/modulator circuit, and an interface circuit is included.

According to the invention, the organic compound layer can be formed bya vapor deposition method, a droplet discharge method, a screen printingmethod, a spin coating method, or the like. A droplet discharge methodis a method for forming a film layer by discharging (jetting) droplets(also referred to dots) of a compound containing a material such as aconductor, an insulator, or the like in arbitrary locations and alsoreferred to as an ink-jet method depending on the method.

According to the invention, a semiconductor device in which data can bewritten (written once, read many) except when manufacturing a memorycircuit and that counterfeits can be prevented. In addition, asemiconductor device according to the invention can operate at highspeed since a transistor using a single crystal semiconductor layerhaving favorable mobility and response speed as a channel portion isincluded. Further, according to the invention, a memory element having asimple structure can be formed; therefore, a semiconductor device havingan inexpensive and highly integrated memory element can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is an explanatory view of one example of the structure of asemiconductor device according to the present invention;

FIGS. 2A and 2B are explanatory views of one example of the structure ofa semiconductor device according to the invention;

FIG. 3 is an explanatory view of one example of the structure of asemiconductor device according to the invention;

FIGS. 4A and 4B are explanatory views of one example of the structure ofa semiconductor device according to the invention;

FIGS. 5A and 5B are explanatory views of one example of the structure ofa semiconductor device according to the invention;

FIGS. 6A and 6B are explanatory views of one example of the structure ofa semiconductor device according to the invention;

FIG. 7 is an explanatory view of one example of the structure of asemiconductor device according to the invention;

FIG. 8 is an explanatory view of one example of the structure of asemiconductor device according to the invention;

FIGS. 9A to 9C are explanatory views of a semiconductor device and adriving method thereof according to the invention;

FIGS. 10A and 10B are explanatory views of a semiconductor device and adriving method thereof according to the invention;

FIGS. 11A to 11C are explanatory views of a semiconductor device and adriving method thereof according to the invention;

FIG. 12 is a view showing one example of a laser irradiation apparatusaccording to the invention;

FIG. 13 is an explanatory view of a semiconductor device and a drivingmethod thereof according to the invention;

FIG. 14 is an explanatory view of one example of the structure of asemiconductor device according to the invention;

FIGS. 15A and 15B are explanatory views of one example of a usage modeof a semiconductor device according to the invention;

FIG. 16 is a view showing current-voltage characteristics of an organicmemory element in a semiconductor device according to the invention;

FIG. 17 is a view showing current-voltage characteristics of an organicmemory element in a semiconductor device according to the invention;

FIGS. 18A to 18C are explanatory views of one example of a usage mode ofa semiconductor device according to the invention;

FIGS. 19A to 19H are explanatory views of one example of a usage mode ofa semiconductor device according to the invention;

FIG. 20 is an explanatory view of one example of a usage mode of asemiconductor device according to the invention;

FIGS. 21A and 21B are views showing current density-voltagecharacteristics of an organic memory element in a semiconductor deviceaccording to the invention;

FIGS. 22A and 22B are views showing current density-voltagecharacteristics of an organic memory element in a semiconductor deviceaccording to the invention;

FIGS. 23A and 23B are views showing current density-voltagecharacteristics of an organic memory element in a semiconductor deviceaccording to the invention; and

FIGS. 24A to 24F are views showing an element structure of an organicmemory element in a semiconductor device according to the invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment modes according to the present invention are explained indetail with reference to the drawings. However, it is easily understoodby those who are skilled in the art that embodiments and details hereindisclosed can be modified in various ways without departing from thepurpose and the scope of the present invention. Therefore, it should benoted that the description of embodiment modes to be given below shouldnot be interpreted as limiting the invention. Through the drawings ofthe embodiments according to the invention, like components are denotedby like numerals as of these embodiments with each other and may not befurther explained.

[Embodiment Mode 1]

In this embodiment mode, one example of the structure of a semiconductordevice according to the present invention is explained with reference toFIGS. 1 to 3.

A semiconductor device according to the invention has a structure inwhich a plurality of circuits is integrated, which includes a layer 351including a plurality of field effect transistors (FETs) and a layer 352including a plurality of memory elements are sequentially stacked (FIG.1). Various circuits are configured by the layer 351 including aplurality of field effect transistors, and the layer 352 including theplurality of memory elements has a memory circuit for storing data.

Next, the cross-sectional structure of a semiconductor device having theabove structure is explained. First, the cross-sectional structure ofthe layer 351 including a plurality of field effect transistors isexplained (FIG. 2A).

A field effect transistor is formed over a single crystal semiconductorsubstrate 302. N-wells 303 and 304 and p-wells 305 and 306 are formed inthe single crystal semiconductor substrate 302, each of which isseparated by a field oxide film 307. The structure is not limited to theabove structure, and a structure provided with only a p-well in the caseof using a n-type single crystal semiconductor substrate or a structureprovided with only a n-well in the case of using a p-type single crystalsemiconductor substrate may be employed.

Gate insulating films 308 to 311 are thin films formed by a thermaloxidation method. Gates 312 to 315 are formed, by a CVD method or thelike, of polycrystalline silicon layers 312 a to 315 a having filmthicknesses of from 100 nm to 300 nm and silicide layers 312 b to 315 bhaving film thicknesses of from 50 nm to 300 nm. Sidewalk 324 to 327 canbe formed by making an insulating layer remain on a side wall of thegates 312 to 315 by anisotropic etching after forming the insulatinglayer over a whole surface of the substrate.

An impurity element which imparts p-type conductivity is added to asource/drain region 328 of a p-channel FET 316 and a source/drain region330 of a p-channel FET 318. On the other hand, an impurity element whichimparts n-type conductivity is added to a source/drain region 329 of an-channel FET 317 and a source/drain region 331 of a n-channel FET 319.

An impurity element which imparts p-type conductivity is added to a lowconcentration impurity region (LDD region) 320 of the p-channel FET 316and a low concentration impurity region (LDD region) 322 of thep-channel FET 318. An impurity element which imparts n-type conductivityis added to a low concentration impurity region (LDD region) 321 of then-channel FET 317 and a low concentration impurity region (LDD region)323 of the n-channel FET 319. These low concentration impurity regionsare regions formed in a self-aligned manner by an ion implantationmethod or an ion doping method. A semiconductor device according to theinvention is not limited to the above structure, and a sidewall and aLDD region are not required to be provided or a salicide (self-alignedsilicide) structure may be employed.

Insulating layers 332 and 333 are provided so as to cover the p-channelFETs 316 and 318 and n-channel FETs 317 and 319. The insulating layers332 and 333 are thin films provided to even a surface.

Source/drain wirings 334 to 341 are wirings which are in contact withthe source/drain regions 328 to 331, respectively, and which fillscontact holes provided for the insulating layers 332 and 333. Insulatinglayers 342 and 343 are provided so as to cover the source/drain wirings334 to 341. The insulating layers 342 and 343 are also thin filmsprovided to even a surface.

Next, a cross-sectional structure of a semiconductor device in which thelayer 352 including a plurality of memory elements over the layer 351including a plurality of field effect transistors is explained (refer toFIG. 2B).

A first conductive layer 345, an organic compound layer 346, and asecond conductive layer 347 are sequentially stacked over the insulatinglayer 343, and this stacked body corresponds to a memory element 350. Aninsulating layer 348 is provided between the organic compound layers346. An insulating layer 349 is provided over a plurality of the memoryelements 350. A minute structure can be easily integrated and asemiconductor device including a memory element having large capacitycan be provided at low cost by providing a plurality of memory elementshaving a simple structure (passive matrix type) over a field effecttransistor as shown in FIG. 2B.

Next, a cross-sectional structure of a semiconductor device which isdifferent from FIG. 2B is explained with reference to FIG. 3.

First conductive layers 361 to 364 are provided so that each of thefirst conductive layers 361 to 364 is connected to a source/drain wiringconnected to a field effect transistor over an insulating layer 343, andorganic compound layers 365 to 368 are provided so as to be in contactwith the first conductive layers 361 to 364, respectively. Further, asecond conductive layer 369 is provided so as to be in contact with theorganic compound layers 365 to 368. The first conductive layers 361 to364 or the second conductive layer 369 can be formed from a knownconductive material such as aluminum (Al), copper (Cu), silver (Ag), orindium tin oxide (ITO) having a light-transmitting property. The organiccompound layers 365 to 368 can be formed by a vapor deposition method ora droplet discharge method. In the case of forming by a dropletdischarge method, a mask is not required since the organic compoundlayer can be selectively formed in a desired place, and in addition,there is an advantage that usability of a material is enhanced sinceonly minimum material is required.

A stacked body of one of the first conductive layers 361 to 364 and thesecond conductive layer 369 corresponds to one of memory elements 371 to374. An insulating layer 370 is provided between the organic compoundlayers 365 to 368. An insulating layer 375 is provided over a pluralityof memory elements 371 to 374. In the structure of the semiconductordevice shown in FIG. 3, a field effect transistor provided for a layer351 including a field effect transistor serves as a switching elementwhen writing or reading to the memory elements 371 to 374 is conducted;therefore, the field effect transistor provided for the layer 351including a field effect transistor is preferably provided using one ofstructures of a p-channel FET and a n-channel FET. According to theabove structure, a semiconductor device which can operate at high speedand in which operating frequency is enhanced can be provided since atransistor using a single crystal semiconductor layer with a favorablemobility or response speed as a channel portion is included.

Next, the structure of a semiconductor device having a function ofnon-contact transmission/reception of data is explained hereinafter withreference to FIGS. 4A to 5B.

A semiconductor device shown in FIGS. 4A and 4B has a structure in whicha plurality of circuits are integrated, in which a layer 401 including aplurality of field effect transistors and a layer 402 including aplurality of memory elements are sequentially stacked, and a conductivelayer 403 serving as an antenna is provided in the periphery of thelayer 402 including the plurality of memory elements (FIGS. 4A and 4B).FIG. 4A is a top view and FIG. 4B is a perspective view.

A cross-sectional structure of a semiconductor device having the abovestructure is explained with reference to FIG. 5A.

In FIG. 5A, a layer 401 including a plurality of field effecttransistors has a p-channel FET 316, a n-channel FET 317, a p-channelFET 318, and a n-channel FET 319. The structures of these FETs are shownin FIG. 2B; therefore, the explanation is omitted.

Insulating layers 342 and 343 are provided so as to cover the p-channelFET 316, the n-channel FET 317, the p-channel FET 318, and the n-channelFET 319, and a layer 402 including a plurality of memory elements isprovided over the insulating layer 343. A conductive layer 403 servingas an antenna is provided in the periphery of the layer 402 includingthe plurality of memory elements.

As for the layer 402 including the plurality of memory elements, a firstconductive layer 445, an organic compound layer 446, and a secondconductive layer 447 are sequentially stacked over the insulating layer343, and this stacked body corresponds to a memory element 450. Aninsulating layer 448 is provided between the organic compound layers446.

The conductive layer 403 serving as an antenna is provided in the samelayer as the first conductive layer 445. Insulating layers 448 and 449are provided over the conductive layer 403. The conductive layer 403serving as an antenna is connected to a transistor included in arectification circuit or a waveform shaping circuit. An alternatingcurrent signal inputted from outside by a non-contact method isprocessed in a rectification circuit or a waveform shaping circuit, thenthe data is exchanged (the data is written and/or read) with an organicmemory element through a reading circuit or a writing circuit. Here, theconductive layer 403 is connected to a source/drain wiring 334 of thep-channel FET 316 and a source/drain wiring 341 of the n-channel FET319. The conductive layer 403 can be formed from a material such ascopper (Cu), aluminum (Al), silver (Ag), or gold (Au). In addition, theconductive layer 403 may be manufactured through the same manufacturingprocess as that of the first conductive layer 445.

Next, a cross-sectional structure of a semiconductor device which isdifferent from the structure shown in FIG. 5A is explained withreference to FIG. 5B. For more details, a cross-sectional structure of asemiconductor device in which a layer 402 including a plurality ofmemory elements has a different structure from that in FIG. 5A isexplained.

In FIG. 5B, a layer 401 including a plurality of field effecttransistors can be provided in the similar way as the structure shown inFIG. 3. As for a layer 402 including a plurality of memory elements,first conductive layers 462 and 463 are provided so as to be connectedto source drain wirings 336 and 338, respectively, and organic compoundlayers 466 and 467 are provided so as to be in contact with the firstconductive layers 462 and 463, respectively. Further, a secondconductive layer 469 is provided so as to be in contact with the organiccompound layers 466 and 467.

A stacked body of any one of the first conductive layers 462 and 463,any one of the organic compound layers 466 and 467, and the secondconductive layer 469 corresponds to any one of memory elements 472 and473. An insulating layer 470 is provided between the organic compoundlayers 466 and 467. Further, an insulating layer 475 is provided over aplurality of the memory elements 472 and 473.

In the structure of the semiconductor device shown in FIG. 5B, each ofthe field effect transistors connected to the first conductive layers462 and 463 serves as a switching element when writing or reading to thememory elements 472 and 473 is conducted; therefore, the above fieldeffect transistors are preferably provided using one of structures of ap-channel FET and a n-channel FET. Further, the other field effecttransistors may be provided using one of structures of a p-channel FETand a n-channel FET, may be provided using both of a p-channel FET and an-channel FET, or may be provided as a CMOS circuit by combining ap-channel FET with a n-channel FET.

As shown in FIGS. 4A to 5B, a semiconductor device having a function ofnon-contact transmission/reception of data can be provided by forming aconductive layer serving as an antenna. Such a semiconductor device canbe utilized for a wireless chip or the like which conducts non-contacttransmission/reception of data. In addition, most of the wireless chipsand the like are required to have a minute structure; however, asemiconductor device having a high-integrated and inexpensive memoryelement can be provided by using the structure shown in FIGS. 5A and 5B.

Next, the structure of a semiconductor device which is different fromthat of FIGS. 4A to 5B in the case of conducting non-contacttransmission/reception of data is explained with reference to FIGS. 6Ato 8.

A semiconductor device according to the invention has a structure inwhich a plurality of circuits are integrated and has a structure ofpasting a substrate provided by sequentially stacking a layer 501including a plurality of field effect transistors and a layer 502including a plurality of memory elements and a substrate provided with aconductive layer 503 serving as an antenna (FIGS. 6A and 6B). FIG. 6A isa top view and FIG. 6B is a perspective view.

A cross-sectional structure of a semiconductor device according to theinvention having the above structure is explained with reference to FIG.7.

A layer 501 including a plurality of field effect transistors has ap-channel FET 316, a n-channel FET 317, a p-channel FET 318, and an-channel FET 319. The structures of these FETs are shown in FIG. 2B;therefore, the explanation is omitted.

A layer 502 including a plurality of memory elements can be provided inthe similar way as a layer 402 including a plurality of memory elementsexplained using FIG. 5A.

A substrate having the layer 501 including the plurality of field effecttransistors and the layer 502 including the plurality of memory elementsand a substrate 504 provided with a conductive layer 503 are pasted witha resin 505 including a conductive particle 506. As a method for formingan element by pasting, for example, after pasting a semiconductorsubstrate having a circular shape and a substrate 504 provided with aplurality of conductive layers, the semiconductor substrate having acircular shape and the substrate 504 which are pasted to each other maybe divided to form individual elements. Further, a substrate 504provided with a plurality of conductive layers may be divided afterpasting a Si substrate which is divided in advance to the substrate 504to form individual elements, or each of a semiconductor substrate and asubstrate 504 may be divided in advance and pasted to form individualelements.

A source/drain wiring 334 of the p-channel FET 316 and a source/drainwiring 341 of the n-channel FET 319 is electrically connected to theconductive layer 503 through the conductive particle 506. Here, a caseof connecting using an anisotropic conductive film including aconductive microparticle is explained; however, a method using aconductive adhesive agent such as Ag paste, Cu paste, or carbon paste,or a method for conducting a solder joint may be used.

Next, a cross-sectional structure of a semiconductor device which isdifferent from a structure shown in FIG. 7 is explained with referenceto FIG. 8. For more details, a cross-sectional structure of asemiconductor device in which a structure of a layer 502 including aplurality of memory elements is different from that in FIG. 7 isexplained.

A layer 501 including a plurality of field effect transistors can beformed as shown in FIG. 5B. A layer 502 including a plurality of memoryelements has the same structure as a layer 402 including a plurality ofmemory elements which is explained using FIG. 5B. A substrate having thelayer 501 including the plurality of field effect transistors and thelayer 502 including the plurality of memory elements and a substrate 504provided with a conductive layer 503 are pasted with a resin 505including a conductive particle 506 in the similar way as the structureshown in FIG. 7. A source/drain wiring 334 and a source/drain wiring 341is electrically connected to the conductive layer 503 through theconductive particle 506.

As shown in FIGS. 6A to 8, a substrate provided by sequentially stackingthe layer 501 including the plurality of field effect transistors andthe layer 502 including the plurality of memory elements and aconductive layer 503 serving as an antenna are pasted; accordingly, thearea of the conductive layer 503 can be formed to have a large sizeeasily compared with a structure shown in FIG. 5A. Conducting resistancecan be kept low by forming the area of the conductive layer to be wide;therefore, communication distance of a semiconductor device can beextended in non-contact transmission/reception of data.

[Embodiment Mode 2]

In this embodiment mode, the structure of a memory element shown inEmbodiment Mode 1 is explained hereinafter.

The present invention has a feature that the memory element(hereinafter, also referred to as an organic memory element) shown inthe above embodiment mode includes an organic compound layer. A memorymay include only an organic memory element or may include other memoryelement. A memory including an organic memory element (hereinafter, alsoreferred to as an organic memory) utilizes the material of an organiccompound and makes electric resistance change by optical action or byelectric action to the organic compound layer.

The structure of the organic memory is explained with reference to FIG.13. The organic memory includes a memory cell array 22 provided with aplurality of memory cells 21 in a matrix, decoders 23 and 24, a selector25, and a reading/writing circuit 26. The structure of the organicmemory shown in FIG. 13 corresponds to the structure (passive matrix) ofa memory element of a layer 402 including a plurality of memory elementsin FIGS. 2B and 5A or a layer 502 including a plurality of organicmemory elements in FIG. 7.

The memory cell 21 includes a first conductive layer which is to beconnected to a bit line Bx (1≦x≦m), a second conductive layer which isto be connected to a word line Wy (1≦y≦n), and an organic compoundlayer. The organic compound layer is provided between the firstconductive layer and the second conductive layer.

Next, a top structure and a cross-sectional structure of the memory cellarray 22 is explained with reference to FIGS. 9A, 9B-1 and 9B-2. Thememory cell array 22 includes a first conductive layer 27 extended in afirst direction, a second conductive layer 28 extended in a seconddirection which is different from the first direction, and an organiccompound layer 29 over a layer (hereinafter, referred to as a substrate30) including a field effect transistor shown in the above embodimentmode. The first conductive layer 27 and the second conductive layer 28are formed so as to intersect with each other and be in a striped shape.An insulating layer 33 is provided between the adjacent organic compoundlayers 29. Further, an insulating layer 34 serving as a protective layeris provided so as to be in contact with the second conductive layer 28.

The first conductive layer 27 and second conductive layer 28 are formedfrom a known conductive material such as aluminum (Al), copper (Cu), orsilver (Ag). The organic compound layer 29 may be formed by a vapordeposition method or a droplet discharge method. In the case of using adroplet discharge method, usability of the material is enhanced sincethe organic compound layer can be selectively provided in each memorycell.

In the case of writing data by light, the second conductive layer 28 isformed so as to have a light-transmitting property. The conductive layerhaving a light-transmitting property is formed from a transparentconductive material such as indium tin oxide (ITO) or formed so as tohave a thickness through which light is transmitted other than atransparent conductive material. In the case where a conductive layerserving as an antenna is provided over a memory element in the aboveembodiment mode, the conductive layer is not provided above the portionof the memory element where data is to be written in order to provide anopening window where light can be emitted. A light shielding film ispreferably provided so that light is not emitted to a field effecttransistor provided below the memory element. Concretely, in the case ofwriting data by applying optical action to a semiconductor device shownin FIG. 2B, at least one layer selected from the insulating layers 332,333, 342, and 343 is formed of a light shielding film. Preferably, atleast one of the insulating layers 342 and 343 is formed of a lightshielding film.

The organic compound layer 29 can be formed from an organic compoundmaterial having conductivity (preferably, conductivity of 10⁻¹⁵ S/cm ormore to 10⁻³ S/cm or less), and a highly hole transporting material suchas an aromatic amine-based (that is, a bond of benzene ring—nitrogen isincluded) compound such as4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviated to α-NPD),4,4′-bis[N-(3-methylphenyl)-N-phenylamino]biphenyl (abbreviated to TPD),4,4′,4″-tris(N,N-diphenylamino)triphenylamine (abbreviated to TDATA),4,4′,4″-tris[N-(3-methylphenyl)-N-phenylamino]triphenylamine(abbreviated to MTDATA), or4,4′-bis(N-(4-(N,N-di-m-tolylamino)phenyl)-N-phenylamino)biphenyl(abbreviated to DNTPD) or a phthalocyanine compound such asphthalocyanine (abbreviated to H₂Pc), copper phthalocyanine (abbreviatedto CuPc), or vanadyl phthalocyanine (abbreviated to VOPc) can be used.

Further, a highly electron transporting material can be used as theorganic compound material, and for example, a material formed from ametal complex or the like having a quinoline skeleton or abenzoquinoline skeleton, such as tris(8-quinolinolato)aluminum(abbreviated to Alq₃), tris(4-methyl-8-quinolinolato)aluminum(abbreviated to Almq₃), bis(10-hydroxybenzo[h]-quinolinato)beryllium(abbreviated to BeBq₂), orbis(2-methyl-8-quinolinolato)-4-phenylphenolato-aluminum (abbreviated toBAlq) or a material such as a metal complex having an oxazole-based orthiazole-based ligand, such, asbis[2-(2-hydroxyphenyl)benzoxazolato]zinc (abbreviated to Zn(BOX)₂) orbis[2-(2-hydroxyphenyl)benzothiazolato]zinc (abbreviated to Zn(BTZ)₂)may be used. Further, in addition to a metal complex, a compound or thelike such as 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole(abbreviated to PBD),1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazole-2-yl]benzene(abbreviated to OXD-7),3-(4-tert-butylphenyl)-4-phenyl-5-(4-biphenylyl)-1,2,4-triazole(abbreviated to TAZ),3-(4-tert-butylphenyl)-4-(4-ethylphenyl)-5-(4-biphenylyl)-1,2,4-triazole(abbreviated to p-EtTAZ), bathophenanthroline (abbreviated to BPhen), orbathocuproin (abbreviated to BCP) may be used.

Further, as other organic compound materials,4-dicyanomethylene-2-methyl-6-[2-(1,1,7,7-tetramethyljulolidine-9-yl)ethenyl]-4H-pyran(abbreviated to DCJT),4-dicyanomethylene-2-t-butyl-6-[2-(1,1,7,7-tetramethyljulolidine-9-yl)ethenyl]-4H-pyran,periflanthene,2,5-dicyano-1,4-bis[2-(10-methoxy-1,1,7,7-tetramethyljulolidine-9-yl)ethenyl]benzene,N,N′-dimethylquinacridone (abbreviated to DMQd), coumarin 6, coumarin545T, tris(8-quinolinolato)aluminum (abbreviated to Alq₃),9,9′-bianthlyl, 9,10-diphenylanthracene (abbreviated to DPA),9,10-bis(2-naphthyl)anthracene (abbreviated to DNA),2,5,8,11-tetra-t-buthylperylene (abbreviated to TBP), or the like can begiven. An anthracene derivative such as9,10-di(2-naphthyl)-2-tert-butylanthracene (abbreviated to t-BuDNA); acarbazole derivative such as 4,4′-bis(N-carbazolyl)biphenyl (abbreviatedto CBP); a metal complex such as bis[2-(2-hydroxyphenyl)pyridinato]zinc(abbreviated to Znpp₂) or bis[2-(2-hydroxyphenyl)benzoxazolate]zinc(abbreviated to ZnBOX); or the like can be used as a material to be abase material in the case of forming a layer in which the light-emittingmaterial is diffused. tris(8-quinolinolato)aluminum (abbreviated toAlq₃), 9,10-bis(2-naphthyl)anthracene (abbreviated to DNA),bis(2-methyl-8-quinolinolato)-4-phenylphenolate-aluminum (abbreviated toBAlq), or the like can be used. The organic compounds described abovecan be provided in a single layer or a stacked layer, and may bearbitrarily selected by a practitioner.

Further, a material in which electric resistance changes by opticalaction or electric action can be used. For example, a conjugated polymerdoped with a compound (photoacid generator) generating acid by means ofabsorbing light can be used. Here, as the conjugated polymer,polyacetylenes, polyphenylene vinylenes, polythiophenes, poly anilines,polyphenylene ethinylenes, or the like can be used. As the photoacidgenerator, aryl sulfonium salt, aryl iodonium salt, o-nitrobenzyltosylate, aryl sulfonic acid p-nitrobenzyl ester, sulfonylacetophenones, Fe-arene complex PF₆ salt, or the like can be used.

As a different structure from the above structure, a rectifying elementmay be provided between the first conductive layer 27 and the organiccompound layer 29 or between the second conductive layer 28 and theorganic compound layer 29 (refer to FIG. 9C). The rectifying elementrefers to a Schottky diode, a PN junction diode, a PIN junction diode,or a transistor in which a gate electrode and a drain electrode areconnected. Obviously, the rectifying element may be a diode having otherstructure. Here, a PN junction diode including semiconductor layers 44and 45 is provided between the first conductive layer and the organiccompound layer. One of the semiconductor layers 44 and 45 is an N-typesemiconductor while the other is a P-type semiconductor. Thus,selectivity of a memory cell and margin of reading and writing can beenhanced by providing the rectifying element.

As described above, an organic memory element shown in this embodimentmode has a simple structure in which an organic compound layer isprovided between a pair of conductive layers; therefore, a manufacturingprocess thereof is simple and a semiconductor device having a highlyintegrated organic memory element can be provided at low cost. Accordingto the above structure, data can be also written (written once, readmany) except when manufacturing the organic memory element; therefore,data can be appropriately written when a user requires. Further, theorganic memory according to the invention is a nonvolatile memory;therefore, an electric battery for maintaining data is not required tobe incorporated, and a small-sized, thin, and lightweight semiconductordevice can be provided. According to the above organic memory, datacannot be rewritten though data can be written (written once, readmany). Accordingly, counterfeits can be prevented and a semiconductordevice with ensured security can be provided by using the organicmemory.

Next, an operation of writing data to the organic memory is explained.Writing data is conducted by optical action or electric action. First,writing data by electric action is explained (refer to FIG. 13). Writingis conducted by changing electric characteristics of a memory cell, andan initial state (condition without electric action) of the memory cellis data “0” and a state of changing electric characteristics is data “1”in this embodiment mode.

In the case of writing data “1” to the memory cell 21, the memory cell21 is selected first by decoders 23 and 24 and a selector 25.Concretely, a predetermined voltage V2 is applied to a word line W3connected to the memory cell 21 by the decoder 24. A bit line B3connected to the memory cell 21 is connected to a reading/writingcircuit 26 by the decoder 23 and the selector 25. Then, a writingvoltage V1 is outputted from the reading/writing circuit 26 to the bitline B3. Thus, voltage Vw=V1−V2 is applied between a first conductivelayer and a second conductive layer included in the memory cell 21. Byselecting electric potential Vw appropriately, an organic compound layer29 provided between the conductive layers is changed physically orelectrically to write data “1”. Concretely, in a reading operationvoltage, electric resistance between the first conductive layer andsecond conductive layer in the state of data “1” may be changed so as tobe drastically lowered compared with electric resistance in the state ofdata “0”. For example, the voltage may be appropriately selected fromthe range of (V1, V2)=(0 V, 5 V to 15 V) or (3 V to 5 V, −12 V to −2 V).The electric potential Vw may be 5V to 15V or −5V to −15′V. In thiscase, the distance between the pair of conductive layers provided so asto interpose the organic compound layer changes in some cases.

A non-selected word line and a non-selected bit line are controlled sothat data “1” is not written to the memory cell which is to be connectedto the non-selected word line and the non-selected bit line. Forexample, the non-selected word line and the non-selected bit line may bein a floating state. Characteristics which can ensure selectivity suchas diode characteristics are required between the first conductive layerand second conductive layer included in the memory cell.

On the other hand, in the case of writing data “0” to the memory cell21, all that is required is that electric action is not applied to thememory cell 21. In circuit operation, for example, although the memorycell 21 is selected by the decoders 23 and 24 and the selector 25 in thesame way as the case of writing data “1”, an output electric potentialfrom the reading/writing circuit 26 to the bit line B3 may be set to beequivalent to an electric potential of a selected word line W3 or anelectric potential of a non-selected word line, and a voltage (forexample, −5 V to 5 V) may be applied between the first conductive layerand second conductive layer included in the memory cell 21 to such adegree that the electric characteristics of the memory cell 21 is notchanged.

Next, writing data by optical action is explained (refer to FIGS. 9B and9C). In this case, an organic compound layer 29 included in an organicmemory element is irradiated with laser light from a conductive layerside having a light transmitting property (second conductive layer 28here). Here, the organic compound layer 29 included in an organic memoryelement in a desired portion is selectively irradiated with laser lightto destroy the organic compound layer 29. The destroyed organic compoundlayer is insulated; therefore, the resistance thereof is increasedcompared with the resistance of other organic memory element. Data iswritten by utilizing the phenomenon that electric resistance between twoconductive layers provided so as to interpose the organic compound layer29 is changed by laser light irradiation. For example, in the case wherean organic memory element including an organic compound layer which isnot irradiated with laser light is made to be data “0”, an organiccompound layer included in an organic memory element in a desiredportion is selectively irradiated with laser light and destroyed toheighten electric resistance in the case of writing data “1”.

In the case of using a conjugated polymer doped with a compound (photoacid generator) which generates acid by absorbing light as the organiccompound layer 29, conductivity increases only the portion of beingirradiated with laser light and a portion of not being irradiated withlaser light has no conductivity when the organic compound layer isirradiated with laser light. Therefore, data is written by utilizing thephenomenon that electric resistance of an organic memory element ischanged by irradiating an organic compound layer included in the organicmemory element in a desired portion with laser light. For example, inthe case where an organic compound layer which is not irradiated withlaser light is made to be data “0”, an organic compound layer in adesired portion is selectively irradiated with laser light to heightenconductivity in the case of writing data “1”.

In the case of laser light irradiation, the change of electricresistance of the organic compound layer 29 included in an organicmemory element depends on the size of the memory cell 21; however, thechange is realized by laser light irradiation narrowed in a diameter ofmicrometer size. For example, when a laser beam having a diameter of 1μm passes at a linear velocity of 10 m/sec, the period of irradiating alayer including an organic compound included in one memory cell 21 withlaser light is 100 nsec. In order to change the phase within time asshort as 100 nsec, the laser power is preferably 10 mW and the powerdensity is preferably 10 kW/mm². When the organic compound layer isselectively irradiated with laser light, it is preferable to use apulsed oscillation laser irradiation apparatus.

Here, one example of a laser irradiation apparatus is explained withreference to FIG. 12. A laser irradiation apparatus 1001 is providedwith a personal computer (hereinafter, referred to as PC 1002) forconducting various controls when laser light is emitted; a laseroscillator 1003 for emitting laser light; a power supply 1004 of thelaser oscillator 1003; an optical system (ND filter) 1005 forattenuating the laser light; an Acousto-Optic Modulator (AOM) 1006 formodulating the intensity of the laser light; an optical system 1007including a lens for shrinking the cross section of the laser light, amirror for changing a light path, and the like; a movement mechanism1009 having a X axis stage and a Y axis stage; a D/A converter 1010 forconverting control data outputted from the PC from a digital one to ananalog one; a driver 1011 for controlling the Acousto-Optic Modulator1006 depending on the analog voltage outputted from the D/A converter; adriver 1012 for outputting a driving signal for driving the movementmechanism 1009; and an autofocusing mechanism 1013 for focusing laserlight on an object to be irradiated (FIG. 12).

A laser oscillator which can oscillate ultraviolet light, visible light,or infrared light can be used as the laser oscillator 1003. An excimerlaser oscillator such as KrF, ArF, XeCl, or Xe; a gas laser oscillatorsuch as He, He—Cd, Ar, He—Ne, or HF; a solid laser oscillator using acrystal such as YAG, GdVO₄, YVO₄, YLF, or YAlO₃ doped with Cr, Nd, Er,Ho, Ce, Co, Ti, or Tm; or a semiconductor laser oscillator such as GaN,GaAs, GaAlAs, or InGaAsP can be used as the laser oscillator. Note thata fundamental wave or a second harmonic to a fifth harmonic arepreferably applied to the solid laser oscillator.

Next, an irradiation method using the laser irradiation apparatus isdescribed. When the movement mechanism 1009 is equipped with a substrate30 provided with an organic compound layer 29, the PC 1002 detects aposition of the organic compound layer 29 which is to be irradiated withlaser light by a camera which is not shown in the drawing. Then, the PC1002 generates movement data for moving the movement mechanism 1009based on the detected position data.

Thereafter, the PC 1002 controls the amount of light which is to beemitted from the Acousto-Optic Modulator 1006 through the driver 1011,and accordingly, laser light emitted from the laser oscillator 1003 isattenuated by the optical system 1005. Then, the amount of light iscontrolled so that a predetermined amount of light is obtained using theAcousto-Optic Modulator 1006. On the other hand, the light path and theshape of beam spot of the laser light outputted from the Acousto-OpticModulator 1006 are changed with the optical system 1007 and the laserlight converges on the lens. Then, the substrate is irradiated with thelaser light.

At this time, the movement mechanism 1009 is controlled to move towardan X direction and a Y direction in accordance with the movement datagenerated by the PC 1002. As a result, a predetermined position isirradiated with the laser light, and the light energy density of thelaser light is converted to the heat energy. Thus, the organic compoundlayer provided over the substrate 30 can be selectively irradiated withlaser light. It is to be noted that laser light irradiation is conductedby moving the movement mechanism 1009; however, laser light may be movedto a X direction and a Y direction by adjusting the optical system 1007.

As described above, a semiconductor device can be easily manufactured inlarge amount by using the above structure according to the invention forwriting data with laser light irradiation. Hence, an inexpensivesemiconductor device can be provided.

Subsequently, an operation of reading data from an organic memory isexplained (refer to FIGS. 13 and 10). Reading data is carried out byusing electronic characteristics between a first conductive layer and asecond conductive layer included in a memory cell, which are differentbetween a memory cell with data “0” and a memory cell with data “1”. Forexample, a reading method utilizing the difference in electricresistance is explained, where the effective electric resistance betweena first conductive layer and a second conductive layer included in amemory cell (herein after also referred to as electric residence ofmemory cell) with data “0” is R0 at a reading voltage, and the electricresistance of a memory cell with data “1” is R1 (R1<<R0) at a readingvoltage. As for a reading/writing circuit, for example, a circuit 26using a resistance element 46 and a differential amplifier 47 shown inFIG. 10A can be conceivable as a structure of a reading portion. Theresistance element 46 has a resistance value Rr (R1<Rr<R0). A transistor48 may be used instead of the resistance element 46 and a clockedinverter 49 can be used instead of the differential amplifier (FIG.10B). A signal or an inverted signal which is Hi when reading isconducted and Lo when reading is not conducted is inputted into theclocked inverter 49. Obviously, a circuit configuration is not limitedto FIGS. 10A and 10B.

In the case of reading data from the memory cell 21, the memory cell 21is selected first by the decoders 23 and 24 and the selector 25.Concretely, a predetermined voltage Vy is applied to a word line Wyconnected to the memory cell 21 by the decoder 24. A bit line Bxconnected to the memory cell 21 is connected to a terminal P of thereading/writing circuit 26 by the decoder 23 and the selector 25.Accordingly, the electric potential Vp of the terminal P is a valuedetermined by dividing Vy and V0 by the resistance element 46(resistance value: Rr) and the memory cell 21 (resistance value: R0 orR1). Therefore, the equation Vp0=Vy+(V0−Vy)*R0/(R0+Rr) holds in the casewhere the memory cell 21 has data “0”. Alternatively, the equation.Vp1=Vy+(V0−Vy)*R1/(R1+Rr) holds in the case where the memory cell 21 hasdata “1”. As a result, by selecting Vref so as to be between Vp0 and Vp1in FIG. 10A or by selecting the change point of the clocked inverter soas to be between Vp0 and Vp1 in FIG. 10B, output electric potential Voutof Lo/Hi (or Hi/Lo) is outputted in accordance with data“0”/“1” so thatreading can be conducted.

For example, assume that the differential amplifier is made to operateat Vdd=3 V, and Vy, V0, and Vref are 0 V, 3 V, and 1.5 V, respectively.On the condition of R0/Rr=Rr/R1=9, Hi is outputted as Vout in accordancewith Vp0=2.7 V when a memory cell has data “0”, or Lo is outputted asVout in accordance with Vp1=0.3 V when a memory cell has data “1”. Inthis way, reading from a memory cell can be conducted.

According to the above method, the state of electric resistance of anorganic memory element is read in a voltage value utilizing thedifference in a resistance value and resistance division. Obviously, thereading method is not limited to this method. For example, reading maybe conducted utilizing the difference in a current value other thanutilizing the difference in electric resistance. In the case whereelectric characteristics of the memory cell have different diodecharacteristics in a threshold voltage in the case of data “0” and data“1”, reading may be conducted utilizing the difference in a thresholdvoltage.

Thus, the structure of an organic memory element can be simply providedaccording to this embodiment mode; therefore, a semiconductor deviceprovided with an organic memory element having a minute structure,namely having large capacity, can be provided at low cost. Further, asfor the above organic memory, data cannot be rewritten though data canbe written once and read many; therefore, counterfeits or the like canbe effectively prevented by the semiconductor device provided with theabove organic memory.

This embodiment mode can be freely combined with the above embodimentmode.

[Embodiment Mode 3]

As described above, a memory is an indispensable component of asemiconductor device according to the present invention. In thisembodiment mode, a memory which has different structure from that of theabove Embodiment Mode 2 is explained with reference to FIGS. 11A to 11C.

A memory 216 includes a memory cell array 222 provided with memory cells221 in a matrix, decoders 223 and 224, a selector 225, and areading/writing circuit 226 in FIG. 11A. The structure of the memory 216here is one example, and other circuits such as a sense amplifier, anoutput circuit, a buffer, and the like may be included.

The memory cell 221 includes a first wiring connected to a bit line Bx(1≦x≦m), a second wiring connected to a word line Wy (1≦y≦n), atransistor 240, and a memory element 241. The memory element 241 has astructure in which an organic compound layer is interposed between apair of conductive layers. A gate electrode of the transistor isconnected to the word line, one of a source electrode and a drainelectrode is connected to the bit line, and the other of the sourceelectrode and the drain electrode is connected to one of two terminalsincluded in the memory element. The other of the two terminals includedin the memory element is connected to a common electrode (electricpotential: Vcom). That is, the structure of the organic memory shown inFIGS. 11A to 11C corresponds to the structure of the memory element(active matrix type) of a layer 402 including a plurality of memoryelements in FIGS. 3 and 5B or a layer 502 including a plurality ofmemory elements in FIG. 8.

For example, as for a semiconductor device shown in FIG. 3, in the caseof writing data by optical action, a second conductive layer 369 isformed from a material having a light-transmitting property such asindium tin oxide (ITO) or formed so as to have a thickness through whichlight is transmitted. At least one selected from insulating layers 342,343, and 370 is preferably formed from a light shielding material sothat light is not emitted to a field effect transistor. In the case ofproviding a conductive layer serving as an antenna as shown in FIGS. 4Ato 8, an opening window is preferably provided in a portion of thememory element in which data is to be written so that the memory elementcan be irradiated with light.

On the other hand, in the case of writing data by electric action, amaterial for first conductive layers 361 to 364 and the secondconductive layer 369 is not especially limited.

Organic compound layers 365 to 368 are explained in the above embodimentmodes, and a structure of a single layer or a stacked layer formed fromany of materials described above can be used.

In the case of using any of organic compound materials as the organiccompound layer, writing data is conducted by optical action such aslaser light or electric action. In the case of using a conjugatedpolymer material doped with a photo acid generator, writing data isconducted by optical action. Reading data is conducted by electricaction in any cases without depending on the material of the organiccompound layer.

Next, an operation of writing data to the memory 216 is explained (referto FIGS. 11A to 11C).

First, an operation of writing data by electric action is explained.Writing is conducted by changing electric characteristics of the memorycell, and an initial state (state without electric action) of the memorycell is data “0” and a state in which electric characteristics have beenchanged is data “1”.

Here, a case of writing data to the memory cell 221 in n-th row and m-thcolumn is explained. In the case of writing data “1” to the memory cell221, the memory cell 221 is selected first by the decoders 223 and 224and the selector 225. Concretely, a predetermined voltage V22 is appliedto a word line Wn connected to the memory cell 221 by the decoder 224.In addition, a bit line Bm connected to the memory cell 221 is connectedto a reading/writing circuit 226 by the decoder 223 and the selector225. Then, a writing voltage V21 is outputted from the reading/writingcircuit 226 to the bit line Bm.

In this way, a transistor 240 included in the memory cell is turned on,and a memory element 241 is electrically connected to a common electrodeand a bit line to apply voltage of approximately Vw=Vcom−V21. An organiccompound layer 29 provided between the conductive layers is changedphysically or electrically by appropriately selecting electric potentialVw so that writing of data “1” is conducted. Concretely, in a readingoperation voltage, electric resistance between the first conductivelayer and second conductive layer in the state of data “1” may bechanged so as to be drastically lowered compared with electricresistance in the state of data “0”, or simply, short circuit may beestablished. The electric potential may be appropriately selected fromthe range of (V21, V22, Vcom)=(5 V to 15 V, 5 V to 15 V, 0 V) or (−12 Vto 0 V, −12 V to 0 V, 3 V to 5 V). The electric potential Vw may be 5 Vto 15 V or −5 V to −15 V. In this case, the distance between the pair ofconductive layers provided so as to interpose the organic compound layerchanges in some cases.

A non-selected word line and a non-selected bit line are controlled sothat data “1” is not written to a memory cell which is to be connectedto the non-selected word line and the non-selected bit line. Concretely,an electric potential (for example, 0 V) for turning off the transistorin the memory cell which is to be connected may be applied to thenon-selected word line, and the non-selected bit line may be in afloating state or an electric potential equivalent to Vcom may beapplied to the non-selected bit line.

On the other hand, in the case of writing data “0” to the memory cell221, all that is required is that electric action is not applied to thememory cell 221. In circuit operation, for example, although the memorycell 221 is selected by the decoders 223 and 224 and the selector 225 inthe same way as the case of writing data “1”, an output electricpotential from the reading/writing circuit 226 to the bit line Bm is setto be equivalent to Vcom or the bit line Bm is set to be in a floatingstate. As a result, a low voltage (for example, −5 V to 5 V) or novoltage is applied to the memory element 241; therefore, electriccharacteristics do not change and writing data “0” is realized.

Next, an operation of writing data by optical action is explained. Inthis case, an organic compound layer is irradiated with laser light froma second conductive layer side having a light-transmitting propertyusing a laser irradiation apparatus 232.

When an organic compound material is used for the organic compoundlayer, the organic compound layer is oxidized or carbonized to beinsulated by laser light irradiation. Then, the resistance value of amemory element 241 which is irradiated with laser light increases,whereas the resistance value of a memory element 241 which is notirradiated with laser light does not change. In the case of using aconjugated polymer material doped with a photo acid generator,conductivity is imparted to the organic compound layer by laser lightirradiation. That is, conductivity is imparted to the memory element 241which is irradiated with laser light, whereas conductivity is notimparted to the memory element 241 which is not irradiated with laserlight.

Subsequently, an operation of reading data by electric action isexplained. Reading data is carried out by using electroniccharacteristics of a memory element 241, which are different between amemory cell with data “0” and a memory cell with data “1”. For example,a reading method by utilizing the difference in electric resistance isexplained, provided that electric resistance of the memory elementincluded in the memory cell with data “0” is R0 in a reading voltage,and electric resistance of the memory element included in the memorycell with data “1” is R1 (R1<<R0) in a reading voltage. As for areading/writing circuit, for example, a circuit 226 using a resistanceelement 246 and a differential amplifier 247 shown in FIG. 11B can beconceivable as a structure of a reading portion. The resistance elementhas a resistance value Rr (R1<Rr<R0). A transistor 250 may be usedinstead of the resistance element 246 and a clocked inverter 251 can beused instead of the differential amplifier (FIG. 11C). Obviously, acircuit configuration is not limited to FIGS. 11A to 11C.

In the case of reading data from the memory cell 221 in n-th row andm-th column, the memory cell 221 is selected first by the decoders 223and 224 and the selector 225. Concretely, a predetermined voltage V24 isapplied to a word line Wn connected to the memory cell 221 by thedecoder 224 to turn on the transistor 240. In addition, a bit line Bmconnected to the memory cell 221 is connected to a terminal P of thereading/writing circuit 226 by the decoder 223 and the selector 225.Accordingly, the electric potential Vp of the terminal P is a valuedetermined by dividing Vcom and V0 by the resistance element 246(resistance value: Rr) and the memory element 241 (resistance value: R0or R1). Therefore, the equation Vp0=Vcom+(V0−Vcom)*R0/(R0+Rr) holds inthe case where the memory cell 221 has data “0”. Alternatively, theequation Vp1=Vcom+(V0−Vcom)*R1/(R1+Rr) holds in the case where thememory cell 221 has data “1”. As a result, by selecting Vref so as to bebetween Vp0 and Vp1 in FIG. 11B or by selecting the change point of theclocked inverter so as to be between Vp0 and Vp1 in FIG. 11C, Lo/Hi (orHi/Lo) of output electric potential Vout is outputted in accordance withdata“0”/“1” so that reading can be conducted.

For example, the differential amplifier is operated at Vdd=3 V, andVcom, V0, and Vref are 0 V, 3 V, and 1.5 V, respectively. On thecondition that the equation R0/Rr=Rr/R1=9 holds and on-resistance of thetransistor 240 can be ignored, Hi is outputted as Vout in accordancewith Vp0=2.7 V when a memory cell has data “0”, or Lo is outputted asVout in accordance with Vp1=0.3 V when a memory cell has data “1”. Inthis way, reading from a memory cell can be conducted.

In accordance with the above method, reading is conducted by a voltagevalue utilizing the difference in a resistance value of the memoryelement 241 and resistance division. Obviously, the reading method isnot limited to this method. For example, reading may be conductedutilizing the difference in a current value other than the methodutilizing the difference in electric resistance. In the case whereelectric characteristics of the memory cell have different diodecharacteristics in threshold voltage in the case of data “0” and data“1”, reading may be carried out by using difference in a thresholdvoltage.

Further, as for the organic memory as described above, data cannot berewritten though data can be written once and read many; therefore,counterfeits or the like can be effectively prevented by thesemiconductor device provided with the above organic memory.

This embodiment mode can be freely combined with the above embodimentmodes.

[Embodiment Mode 4]

In this embodiment mode, a communication procedure using a semiconductordevice according to the present invention as a wireless chip 3060 isbriefly explained hereinafter (refer to FIG. 14).

First, an antenna 3050 included in the wireless chip 3060 receives anelectric wave from a reader/writer 3070. Then, electromotive force isgenerated by resonance action in a power generation means 3030. An ICchip 3040 included in the wireless chip 3060 is started, and data in amemory means 3010 is converted to a signal by a control means 3020.

Next, a signal is sent from the antenna 3050 included in the wirelesschip 3060. Then, the reader/writer 3070 receives a transmitted signal bythe antenna included in the reader/writer 3070. The received signal istransmitted to a data processing system through a controller included inthe reader/writer 3070, and data processing is conducted using software.In the above communication procedure, a coiled antenna is used and anelectromagnetic induction method using magnetic flux generated byinduction between a coil of a wireless chip and a coil of areader/writer is illustrated. However, an electric wave method using anelectric wave of a microwave band may be adopted.

As for the wireless chip in this embodiment mode, a passive type forsupplying a power supply voltage to an element formation layer by anelectric wave without mounting a power supply (buttery) or an activetype for supplying a power supply voltage to an element formation layerwith mounting a power supply (buttery) instead of an antenna may beused, or a power supply voltage may be supplied by an electric wave anda power supply.

The wireless chip 3060 has advantages that non-contact communication ispossible; multiple reading is possible; writing data is possible;processing into various shapes is possible; directivity is wide and awide recognition range is provided depending on the selected frequency;and the like. The wireless chip 3060, in non-contact wirelesscommunication, can be applied to an IC tag which can identify individualinformation of a person or a thing, an adhesive label which is enabledto be attached to an object by label processing, a wristband for anevent or an amusement, or the like. In addition, the wireless chip 3060may be processed with a resin material and may be directly fixed to ametal obstructing wireless communication. Further, the wireless chip3060 can be utilized for an operation of a system such as anentering-leaving management system or a checkout system.

Next, one mode of the actual use of the wireless chip practically isexplained. A reader/writer 3200 is provided on the side of a portableterminal including a display portion 3210, and a wireless chip 3230 isprovided on the side of an article 3220 (refer to FIG. 15A). When thereader/writer 3200 is held against the wireless chip 3230 included inthe article 3220, information relating to a product, such as a rawmaterial and a place of origin of the article, a test result in eachproduction process, a history of distribution process, or further,description of the product is displayed in the display portion 3210. Inaddition, a product 3260 can be inspected by using a reader/writer 3240and a wireless chip 3250 provided on the product 3260 when the product3260 is transported with a belt conveyor (refer to FIG. 15B). In thismanner, information can be easily obtained, and a high function and ahigh added value are realized by utilizing a wireless chip for a system.

This embodiment mode can be freely combined with the above embodimentmodes.

[Embodiment Mode 5]

In the case of integrating a semiconductor device according to thepresent invention with an organic memory, it is preferable to havefeatures as follows.

A reading period is preferably 1 nsec to 100 μsec to be operated inoperating frequency (typically, 10 kHz to 1 MHz) of a logic circuit in awireless chip. In this invention, a reading operation is not required tomake characteristics of an organic compound change; therefore, a readingperiod of 100 μsec or less can be realized.

Obviously, it is preferable that a writing period per bit is shorter;however, writing operation is not so much conducted, and a permissiblerange is 100 nsec/bit to 10 msec/bit depending on the usage. Forexample, in the case of writing of 256 bit, 2.56 seconds are requiredwhen the writing period per bit is 10 msec/bit. In this invention,characteristics of an organic compound are required to be made to changein a writing period and a writing operation requires more time than areading operation; however, a writing period of 10 msec or less can berealized. A writing period can be shortened by heightening a writingvoltage or parallelizing writing.

A memory capacity of the memory is preferably approximately 64 bit to 64Mbit. In the case where only UID (Unique Identifier) and other littleinformation are stored in a wireless chip and a main data is stored inother file server as a usage mode of the wireless chip, a memorycapacity of the memory is preferably approximately 64 bit to 8 kbit. Inthe case of storing data such as history information in a wireless chip,the memory capacity of the memory is preferably larger, andapproximately 8 kbit to 64 Mbit is preferable.

The communication distance of a wireless chip closely relates to powerconsumption of a chip, and in general, a long communication distance canbe realized when power consumption is small. In particular, powerconsumption is preferably 1 mW or less in reading operation. In writingoperation, there is a case where a communication distance may be shortaccording to the usage, and power consumption which is larger than thatof reading operation is permissive, and for example, power consumptionis preferably 5 mW or less. In this invention, power consumption of anorganic memory of 10 μW to 1 mW can be realized in reading operation,although it depends obviously on memory capacity or operating frequency.Power consumption of writing operation increases since a higher voltagethan that of reading operation is required. Power consumption of 50 μWto 5 mW can be realized in writing operation, although it also dependson memory capacity or operating frequency.

The area of the memory cell is preferably small, and 100 nm square to 30μm square can be realized. In a passive type having no transistor in amemory cell, the area of the memory cell is determined depending on thewidth of wirings, and a small-sized memory cell having approximately aminimum processing dimension can be realized. In an active matrix typehaving one transistor in a memory cell, a small-sized area of the memorycell compared with a DRAM having a capacitor element or a SRAM using aplurality of transistors can be realized although the area of disposinga transistor is required. The area of a memory cell array of 1 kbitmemory can be 1 mm square or less by realizing the area of the memorycell of 30 um square or less. The area of a memory cell array of 64 Mbitmemory can be 1 mm square or less by realizing the area of the memorycell of approximately 100 nm square. As a result, the area of a chip canbe made to be small.

These features of an organic memory depend on characteristics of amemory element. As characteristics of the memory element, a voltagerequired for electrical writing is preferably a low voltage within therange that writing is not conducted in reading, and may be 5 V to 15 V,more preferably, 5 V to 10 V. A current value flowing in the memoryelement in writing is preferably approximately 1 nA to 30 μA. Accordingto such values, power consumption can be lowered and the area of a chipcan be reduced by miniaturizing a boosting circuit. A period requiredfor changing characteristics by applying voltage to the memory elementis preferably 100 nsec to 10 msec corresponding to the writing period ofa bit of the organic memory. The area of the memory element ispreferably 100 nm square to 10 μm square. According to such values, thearea of the chip can be reduced by realizing a small-sized memory cell.

This embodiment mode can be freely combined with the above embodimentmode.

[Embodiment Mode 6]

The usage of a semiconductor device according to the present inventionis wide-ranging. For example, the semiconductor device can be used foran electronic apparatus in which information is stored and displayed.Concrete examples of the above electronic apparatus are shown in FIGS.18A to 18C.

FIG. 18A shows a rice cooker, which includes a chassis 2001, a displayportion 2002, an operation button 2003, a lid 2004, a handle 2005, andthe like. Various data can be stored and the data can be displayed usingthe display portion 2002 by providing a semiconductor device illustratedin the embodiment modes described above for a rice cooker. For example,information one wants to know can be easily searched by operating theoperation button 2003 by a user with a recipe (the amount of water, theamount of rice, or the like) for making white rice, rice porridge, ricewith edible wild plants, or the like stored in the rice cooker inadvance. Moreover, data can be written (written once, read many) by auser as for, for example, the softness or hardness of rice or the liketo suit the preference of the user.

FIG. 18B shows a microwave oven, which includes a chassis 2101, adisplay portion 2102, an operation button 2103, a window 2104, a handle2105, and the like. Various data can be stored and the data can bedisplayed using the display portion 2102 by providing a semiconductordevice illustrated in the embodiment modes described above for amicrowave oven. For example, information one wants to know can be easilysearched by operating the operation button 2103 by a user with a recipefor various foods, the heating time and thawing time of the materialthereof, or the like stored in the microwave oven in advance. Moreover,a user's original recipe or the like which is not stored as data can bewritten as data.

FIG. 18C shows a washing machine, which includes a chassis 2201, adisplay portion 2202, an operation key 2203, a lid 2204, a hose 2205,and the like. Various data can be stored and the data can be displayedusing the display portion 2202 by providing a semiconductor deviceillustrated in the embodiment modes described above for a washingmachine. For example, information one wants to know can be easilysearched by operating the operation button 2203 by a user with a washingmethod, the amount of water to the amount of garments, the amount ofdetergent, and the like stored in the washing machine in advance.Moreover, a washing method can be written as data by a user to suit thepreference of the user.

The application of a semiconductor device according to the invention isnot limited to that shown in FIGS. 18A to 18C, and the semiconductordevice can be utilized for a television receiver; a handheld terminalsuch as a cellular phone; a digital camera; a video camera, a navigationsystem, or the like. The case of utilizing a semiconductor deviceaccording to the invention for a cellular phone is explained withreference to FIG. 20. The cellular phone includes chassis 2700 and 2706,a panel 2701, a housing 2702, a printed wiring board 2703, an operationbutton 2704, a buttery 2705, and the like. The panel 2701 isincorporated into the housing 2702 so as to be freely detached/attached,and the housing 2702 is fitted into the printed wiring board 2703. Theshape and measurement of the housing 2702 can be appropriately changeddepending on an electronic apparatus into which the panel 2701 isincorporated. A plurality of semiconductor devices which are packagedare mounted on the printed wiring board 2703, and the semiconductordevice according to the invention can be used as one of the plurality ofsemiconductor devices. Each of the plurality of semiconductor devicesmounted on the printed wiring board 2703 serves as any one of acontroller, a central processing unit (CPU), a memory, a power supplycircuit, a audio processing circuit, a sending/receiving circuit, andthe like.

The panel 2701 is integrated with the printed wiring board 2703 througha connection film 2708. The panel 2701, the housing 2702, and theprinted wiring board 2703 described above are placed inside the chassis2700 and 2706 along with the operation button 2704 and the buttery 2705.A pixel region 2709 included in the panel 2701 is disposed so as to bevisibly confirmed from an opening window provided for the chassis 2700.

The semiconductor device according to the invention has features ofsmall size, thinning, and lightweight. According to the features, alimited space inside the chassis 2700 and 2706 of an electronicapparatus can be effectively utilized. A semiconductor device accordingto the invention has a feature of including a memory circuit having asimple structure, and according to the above feature, an electronicapparatus using a semiconductor device having an inexpensive and highlyintegrated memory circuit can be provided. Further, the semiconductordevice according to the invention has a feature of including a memorycircuit which is nonvolatile and able to write once and read many, andaccording to the above feature, an electronic apparatus in which a highfunction and a high added value are realized can be provided. Inaddition, the semiconductor device according to the invention has atransistor in which a single crystal semiconductor layer havingfavorable mobility or favorable response speed is used as a channelportion; therefore, an electronic apparatus using a semiconductor devicewhich can operate at high speed and in which operating frequency isenhanced can be provided.

The semiconductor device according to the invention can be utilized fora wireless chip. For example, the semiconductor device can be used bybeing provided for paper money, coins, securities, certificates, bearerbonds, packing containers, documents, recording media, commodities,vehicles, foods, garments, health articles, livingwares, medicines,electronic devices, and the like. These examples are explained withreference to FIGS. 19A to 19H.

The paper money and coins are money distributed in the market andinclude currency such as cash vouchers available in a certain area inthe same way as money, and memorial coins. The securities refer tochecks, stock certificates, promissory notes, and the like (refer toFIG. 19A). The certificates refer to driver's licenses, certificates ofresidence, and the like (refer to FIG. 19B). The bearer bonds refer tostamps, rise coupons, various merchandise coupons, and the like (referto FIG. 19C). The packing containers refer to wrapping paper for lunch,plastic bottles, and the like (refer to FIG. 19D). The documents referto volumes, books and the like (refer to FIG. 19E). The recording mediarefer to DVD software, video tapes, and the like (refer to FIG. 19F).The vehicles refer to wheeled vehicles such as bicycles, vessels, andthe like (refer to FIG. 19G). The commodities refer to bags, glasses,and the like (refer to FIG. 19H). The foods refer to food articles,drinks, and the like. The garments refer to clothes, chaussures, and thelike. The health articles refer to medical appliances, healthappliances, and the like. The livingwares refer to furniture, lightingequipment, and the like. The medicines refer to medical products,pesticides, and the like. The electronic apparatuses refer to liquidcrystal display apparatuses, EL display apparatuses, televisionapparatuses (TV sets or flat-screen televisions), cellular phones, andthe like.

Counterfeits can be prevented by providing a wireless chip to the papermoney, coins, securities, certificates, bearer bonds, and the like. Theefficiency of an inspection system or a system used in a rental shop canbe promoted by providing a wireless chip to the packing containers,documents, recording media, commodities, foods, livingwares, electronicdevices, or the like. By providing a wireless chip to each of thevehicles, health articles, medicines, and the like, counterfeits ortheft can be prevented, further, medicines can be prevented from takingmistakenly. The wireless chip is provided for goods by pasting on theirsurfaces or embedding thereinto. For example, the wireless chip may beembedded in a paper in case of a book or embedded in an organic resin incase of a package formed from the organic resin. In the case of writing(writing once, reading many) by optical operation afterward, atransparent material is preferably used so that light can be emitted toa memory element provided for a chip. Further, counterfeits can beeffectively prevented by using a memory element in which once-writtendata cannot be rewritten. Problems such as privacy after a userpurchases a product can be solved by providing a system for erasing dataof a memory element provided for a wireless chip.

The efficiency of an inspection system, a system used in a rental shop,or the like can be promoted by providing a wireless chip for, forexample, packing containers, recording media, commodities, foods,garments, livingwares, electronic devices, or the like. Counterfeits ortheft can be prevented by providing a wireless chip for vehicles.Individual creatures can be easily identified by implanting a wirelesschip in creatures such as animals. For example, year of birth, sex,breed, and the like can be easily identified by implanting a wirelesschip in creatures such as domestic animals.

As described above, a semiconductor device according to the inventioncan be provided for everything as long as they are goods which storedata. This embodiment mode can be freely combined with the aboveembodiment modes.

[Embodiment 1]

In this embodiment, a result of writing data by electric action to anorganic memory element manufactured over a substrate is explained.

An organic memory element is an element in which a first conductivelayer, a first organic compound layer, a second organic compound layer,and a second conductive layer are sequentially stacked over a substrate.The first conductive layer is formed from a compound of silicon oxideand indium tin oxide; the first organic compound layer,4,4′-bis[N-(3-methylphenyl)-N-phenylamino]biphenyl (this material may beabbreviated to TPD); the second organic compound layer,4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (this material may beabbreviated to α-NPD); and the second conductive layer, aluminum. Thefirst organic compound layer is formed so as to have a film thickness of10 nm; and the second organic compound layer, 50 nm. The size of theelement is 2 mm×2 mm.

First, a measurement result of current-voltage characteristics of theorganic memory element before writing data by electric action and afterwriting data by electric action is explained with reference to FIG. 16.

In FIG. 16, a horizontal axis indicates a voltage value, a vertical axisindicates a current value, plots 261 indicate current-voltagecharacteristics of the organic memory element before writing data byelectric action, and plots 262 indicate current-voltage characteristicsof the organic memory element after writing data by electric action. Theelectric action is conducted by increasing voltage gradually from 0V. Asshown in the plots 261, a current value increases gradually as voltageincreases, and a current value drastically increases approximately at 20V. That is, this shows that writing to this element can be conducted at20 V. Therefore, a curve in the range of 20 V or less of the plots 261shows current-voltage characteristics of a memory cell in which writingis not conducted and the plots 262 show current-voltage characteristicsof the memory cell in which writing is conducted.

FIG. 16 shows a substantial change in current-voltage characteristics ofan organic memory element before and after writing data. For example, acurrent value before writing data is 4.8×10⁻⁵ mA at an applied voltage 1V, whereas a current value after writing data is 1.1×10² mA at anapplied voltage 1 V; accordingly, a current value changes forseven-digit before and after writing data.

As described above, a resistance value of the organic memory elementchanges before and after writing data, and the organic memory elementcan serve as a memory circuit when the change of the resistance value ofthis organic memory element is read by a voltage value or a currentvalue.

In the case of using an organic memory element as described above as amemory circuit, a predetermined voltage value (voltage value which isenough to keep from shortening) is applied to the organic memory elementeach time reading operation of data is conducted, then the resistancevalue is read. Therefore, current-voltage characteristics of the aboveorganic memory element are required to have a characteristic which doesnot change even through reading operation is repeatedly conducted, thatis, even though a predetermined voltage value is repeatedly applied.

A measurement result of current-voltage characteristics of an organicmemory element after reading data is explained with reference to FIG.17.

In this experiment, current-voltage characteristics of the organicmemory element are measured each time reading operation of data isconducted one time. The reading operation of data is conducted fivetimes in total; therefore, the current-voltage characteristics of theorganic memory element are measured five times in total. Thecurrent-voltage characteristics are measured for two organic memoryelements: an organic memory element in which a resistance value ischanged and an organic memory element in which a resistance value is notchanged, both of which result from writing data by electric action.

In FIG. 17, a horizontal axis indicates a voltage value, a vertical axisindicates a current value, plots 272 indicate current-voltagecharacteristics of an organic memory element in which a resistance valueis changed by writing data by electric action, and plots 271 indicatecurrent-voltage characteristics of a organic memory element in which aresistance value is not changed.

As shown in the plots 271, current-voltage characteristics of theorganic memory element before writing data show a favorablereproducibility especially at a voltage value of 1 V or more. Similarly,as shown in the plots 272, current-voltage characteristics of theorganic memory element in which a resistance value is changed by writingdata show a favorable reproducibility especially at a voltage value of 1V or more.

From the above-described results, current-voltage characteristics arenot changed even though reading operation of data is repeatedlyconducted a plurality of times. Hence, the above organic memory elementcan be used as a memory circuit.

[Embodiment 2]

As for samples 1 to 6 in which an organic memory element is manufacturedover a substrate as shown in FIGS. 24A to 24F, a measurement result ofcurrent density-voltage characteristics when data is electricallywritten to an organic memory element is shown in FIGS. 21A to 23B. Here,writing is conducted by applying voltage to the organic memory elementand shortening the organic memory element.

In each of FIGS. 21A to 23B, a horizontal axis indicates voltage, avertical axis indicates a current density value, circular plots indicatea measurement result of current density-voltage characteristics of theorganic memory element before writing data, and square plots indicate ameasurement result of current density-voltage characteristics of theorganic memory element after writing data. The size of each samples 1 to6 in a horizontal plane is 2 mm×2 mm.

The sample 1 is an element in which a first conductive layer, a firstorganic compound layer, and a second conductive layer are sequentiallystacked. Here, as shown in FIG. 24A, the first conductive layer isformed from ITO containing silicon oxide; the first organic compoundlayer, TPD; and the second conductive layer, aluminum. The first organiccompound layer is formed so as to have a thickness of 50 nm. Ameasurement result of current density-voltage characteristics of thesample 1 is shown in FIG. 21A.

The sample 2 is an element in which a first conductive layer, a firstorganic compound layer, and a second conductive layer are sequentiallystacked. Here, as shown in FIG. 24B, the first conductive layer isformed from ITO containing silicon oxide; the first organic compoundlayer, TPD added with2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (this material maybe abbreviated to F4-TCNQ); and the second conductive layer, aluminum.The first organic compound layer is formed so as to have a thickness of50 nm and by adding 0.01 wt % F4-TCNQ. A measurement result of currentdensity-voltage characteristics of the sample 2 is shown in FIG. 21B.

The sample 3 is an element in which a first conductive layer, a firstorganic compound layer, a second organic compound layer, and a secondconductive layer are sequentially stacked. Here, as shown in FIG. 24C,the first conductive layer is formed from ITO containing silicon oxide;the first organic compound layer, TPD; the second organic compoundlayer, F4-TCNQ; and the second conductive layer; aluminum. The firstorganic compound layer is formed so as to have a thickness of 50 nm, andthe second organic compound layer is formed so as to have a thickness of1 nm. A measurement result of current density-voltage characteristics ofthe sample 3 is shown in FIG. 22A.

The sample 4 is an element in which a first conductive layer, a firstorganic compound layer, a second organic compound layer, and a secondconductive layer are sequentially stacked. Here, as shown in FIG. 24D,the first conductive layer is formed from ITO containing silicon oxide;the first organic compound layer, F4-TCNQ; the second organic compoundlayer, TPD; and the second conductive layer, aluminum. The first organiccompound layer is formed so as to have a thickness of 1 nm, and thesecond organic compound layer is formed so as to have a thickness of 50nm. A measurement result of current density-voltage characteristics ofthe sample 4 is shown in FIG. 22B.

The sample 5 is an element in which a first conductive layer, a firstorganic compound layer, a second organic compound layer, and a secondconductive layer are sequentially stacked. Here, as shown in FIG. 24E,the first conductive layer is formed from ITO containing silicon oxide;the first organic compound layer, TPD added with F4-TCNQ; the secondorganic compound layer, TPD; and the second conductive layer, aluminum.The first organic compound layer is formed so as to have a thickness of40 nm and by adding 0.01 wt % F4-TCNQ, and the second organic compoundlayer is formed so as to have a thickness of 40 nm. A measurement resultof current density-voltage characteristics of the sample 5 is shown inFIG. 23A.

The sample 6 is an element in which a first conductive layer, a firstorganic compound layer, a second organic compound layer, and a secondconductive layer are sequentially stacked. Here, as shown in FIG. 24F,the first conductive layer is formed from ITO containing silicon oxide;the first organic compound layer, TPD; the second organic compoundlayer, TPD added with F4-TCNQ; and the second conductive layer,aluminum. The first organic compound layer is formed so as to have athickness of 40 nm. The second organic compound layer is formed so as tohave a film thickness of 10 nm and by adding 0.01 wt % F4-TCNQ. Ameasurement result of current density-voltage characteristics of thesample 6 is shown in FIG. 23B.

The experiment results shown in FIGS. 21A to 23B also show a substantialchange in current density-voltage characteristics of the organic memoryelement before and after shortening the organic memory element. In suchan organic memory element of these samples, there is reproducibility involtage which shortens each organic memory element, and the discrepancyis within 0.1 V.

Next, a writing voltage and characteristics before and after writing ofthe samples 1 to 6 are shown in Table 1.

TABLE 1 writing voltage(V) R(1 V) R(3 V) sample 1 8.4 1.9E+07 8.4E+03sample 2 4.4 8.0E+08 2.1E+02 sample 3 3.2 8.7E+04 2.0E+02 sample 4 5.03.7E+04 1.0E+01 sample 5 6.1 2.0E+05 5.9E+01 sample 6 7.8 2.0E+042.5E+02

In Table 1, a writing voltage (V) indicates an applied voltage when eachorganic memory element is shortened. R(1V) is a value that currentdensity at applying 1 V to the organic memory element after writing isdivided by current density at applying 1 V to the organic memory elementbefore writing. Similarly, R(3V) is a value that current density atapplying 3 V to the organic memory element after writing is divided bycurrent density at applying 3 V to the organic memory element beforewriting. That is, Table 1 indicates the change of current density beforeand after writing to the organic memory element. In the case where anapplied voltage is 1 V, it is found that the difference in currentdensity of the organic memory element is as large as 4-plex or morecompared with the case where an applied voltage is 3 V.

This application is based on Japanese Patent Application serial No.2004-308838 field in Japan Patent Office on Oct. 22, 2004, the contentsof which are hereby incorporated by reference.

1. A semiconductor device comprising: a field effect transistor having achannel region formed in a single crystal semiconductor substrate; and amemory circuit provided above the field effect transistor, wherein saidmemory circuit comprises: a first conductive layer, an organic compoundlayer over the first conductive layer, and a second conductive layerformed over the organic compound layer, wherein the organic compoundlayer comprises a conjugated polymer doped with a compound whichgenerates acid by absorbing light.
 2. The semiconductor device accordingto claim 1, wherein the second conductive layer has a light transmittingproperty.
 3. The semiconductor device according to claim 1, whereinresistance of the organic compound layer changes irreversibly by writingprocessing that voltage is applied.
 4. The semiconductor deviceaccording to claim 1, wherein a distance between the first conductivelayer and the second conductive layer changes when data is written tothe memory circuit.
 5. The semiconductor device according to claim 1,wherein the organic compound layer is formed from an electrontransporting material or a hole transporting material.
 6. Thesemiconductor device according to claim 1, wherein the organic compoundlayer includes a material in which electric resistance changes beforeand after emitting light.
 7. The semiconductor device according to claim6, wherein conductivity of the organic compound layer changes before andafter emitting laser light.
 8. The semiconductor device according toclaim 1, wherein said semiconductor device further comprises one or aplurality of circuits selected from the group consisting of a powersupply circuit, a clock generator circuit, a data demodulator/modulatorcircuit, and an interface circuit.
 9. The semiconductor device accordingto claim 1, wherein the compound which generates acid comprises at leastone of aryl sulfonium salt, aryl iodonium salt, o-nitrobenzyl tosylate,aryl sulfonic acid p-nitrobenzyl ester, sulfonyl acetophenones, andFe-arene complex PF₆ salt.
 10. The semiconductor device according toclaim 1, wherein the memory circuit has a passive matrix type structure.11. A semiconductor device comprising: a field effect transistor havinga channel region formed in a single crystal semiconductor substrate; amemory circuit provided above the field effect transistor, wherein saidmemory circuit comprises: a first conductive layer, an organic compoundlayer over the first conductive layer, and a second conductive layerformed over the organic compound layer; and a third conductive layerserving as an antenna, and wherein the third conductive layer serving asthe antenna and the first conductive layer are provided in a same layer.12. The semiconductor device according to claim 11, wherein the secondconductive layer has a light transmitting property.
 13. Thesemiconductor device according to claim 11, wherein resistance of theorganic compound layer changes irreversibly by writing processing thatvoltage is applied.
 14. The semiconductor device according to claim 11,wherein a distance between the first conductive layer and the secondconductive layer changes when data is written to the memory circuit. 15.The semiconductor device according to claim 11, wherein the organiccompound layer is formed from an electron transporting material or ahole transporting material.
 16. The semiconductor device according toclaim 11, wherein the organic compound layer includes a material inwhich electric resistance changes before and after emitting light. 17.The semiconductor device according to claim 16, wherein conductivity ofthe organic compound layer changes before and after emitting laserlight.
 18. The semiconductor device according to claim 11, wherein saidsemiconductor device further comprises one or a plurality of circuitsselected from the group consisting of a power supply circuit, a clockgenerator circuit, a data demodulator/modulator circuit, and aninterface circuit.
 19. The semiconductor device according to claim 11,wherein the organic compound layer comprises a conjugated polymer dopedwith a compound which generates acid by absorbing light.
 20. Thesemiconductor device according to claim 19, wherein the compound whichgenerates acid comprises at least one of aryl sulfonium salt, aryliodonium salt, o-nitrobenzyl tosylate, aryl sulfonic acid p-nitrobenzylester, sulfonyl acetophenones, and Fe-arene complex PF₆ salt.
 21. Thesemiconductor device according to claim 11, wherein the memory circuithas a passive matrix type structure.
 22. A semiconductor devicecomprising: a field effect transistor having a channel region formed ina single crystal semiconductor substrate; a memory circuit providedabove the field effect transistor, wherein said memory circuitcomprises: a first conductive layer, an organic compound layer over thefirst conductive layer, and a second conductive layer formed over theorganic compound layer; and a third conductive layer serving as anantenna, wherein the third conductive layer serving as the antenna iselectrically connected to the field effect transistor.
 23. Thesemiconductor device according to claim 22, wherein the third conductivelayer serving as the antenna is electrically connected to the fieldeffect transistor through a conductive particle.
 24. The semiconductordevice according to claim 22, wherein the second conductive layer has alight transmitting property.
 25. The semiconductor device according toclaim 22, wherein resistance of the organic compound layer changesirreversibly by writing processing that voltage is applied.
 26. Thesemiconductor device according to claim 22, wherein a distance betweenthe first conductive layer and the second conductive layer changes whendata is written to the memory circuit.
 27. The semiconductor deviceaccording to claim 22, wherein the organic compound layer is formed froman electron transporting material or a hole transporting material. 28.The semiconductor device according to claim 22, wherein the organiccompound layer includes a material in which electric resistance changesbefore and after emitting light.
 29. The semiconductor device accordingto claim 28, wherein conductivity of the organic compound layer changesbefore and after emitting laser light.
 30. The semiconductor deviceaccording to claim 22, wherein said semiconductor device furthercomprises one or a plurality of circuits selected from the groupconsisting of a power supply circuit, a clock generator circuit, a datademodulator/modulator circuit, and an interface circuit.
 31. Thesemiconductor device according to claim 22, wherein the organic compoundlayer comprises a conjugated polymer doped with a compound whichgenerates acid by absorbing light.
 32. The semiconductor deviceaccording to claim 31, wherein the compound which generates acidcomprises at least one of aryl sulfonium salt, aryl iodonium salt,o-nitrobenzyl tosylate, aryl sulfonic acid p-nitrobenzyl ester, sulfonylacetophenones, and Fe-arene complex PF₆ salt.
 33. The semiconductordevice according to claim 22, wherein the memory circuit has a passivematrix type structure.